Field of the Invention
The present invention relates to a bipodal-peptide binder and a method for preparing the same.
Background of Technique
An antibody is an immunoglobulin protein as a serum protein which is produced by B cells, and specifically recognizes a particular region of foreign antigen to inactivate or incapacitate antigen. Using high-specification and high-affinity of antigen-antibody reaction and applying a variety of antibodies capable of discriminating 10 million antigens, numerous antibody products including diagnostics and therapeutics have been developed nowadays. Twenty one monoclonal antibodies have been approved by FDA until now, and antibodies such as Rituximab and Herceptin have been proved to have an excellent efficacy over 50% of subjects who exhibit no response to other therapies. In practice, the utilization of monoclonal antibodies results in successful clinic treatment including lymphoma, colorectal cancer or breast cancer. Whole market size of therapeutic antibodies might be evaluated to be in an annual average of 20% growth rate from 10 billion dollars in 2004 to 30 billion dollars in 2010 and predicted to be increased in a geometrical progression. There has been emerging focus on development of new drug using antibody because of: (a) short development period of drug; (b) economical investment cost; and (c) feasible prediction of adverse effects. Additionally, antibody as a herb medicine has no influence on a human body and is beneficial to a subject since it has half-life much longer than drugs with a low molecular weight. In spite of these availabilities, monoclonal antibodies may induce severe allergic or hypersensitive responses in human body due to recognition as a foreign antigen. Furthermore, clinical utilization of a monoclonal antibody with an anti-cancer activity has the following drawbacks: (a) high therapeutics cost due to high production cost; and (b) expensive licensing fees because intellectual property rights protect widespread techniques such as culture and purification method of antibodies.
To overcome these problems, it is earlier beginning to develop antibody alternatives in USA and EU. The antibody alternatives are designed as a recombinant protein having constant and variable domain like an antibody, of which the size is small and a particular region of a stable protein is replaced by random amino acid sequence, leading to produce a library, and the library is utilized for screening a target molecules to isolate a molecule with high affinity and excellent specificity. For example, it has been reported that avimer and affibody of antibody alternatives have a superior affinity to a target molecule in picomole level. Generally, the small-sized and stable antibody alternatives have been reported to penetrate into cancer cells in a feasible manner and to induce immune responses in a low level. First of all, the antibody alternatives may avoid antibody patent barriers and have excellent advantages such as (a) low production cost and (b) feasible massive purification from bacteria. Currently, 40 antibody alternatives have been known, and the example of antibody alternatives commercially attempted in ventures or international pharmaceuticals includes fibronectin type III domain, lipocalin, LDLR-A domain, crystalline, protein A, ankyrin repeat or BPTI protein, which have high affinity to a target molecule in the level of picomole. Of them, FDA clinic experiments for adnectin, avimer or Kunitz domain are on-going at present.
The present invention focused on a peptide-based antibody alternative different from conventionally protein-based antibody alternatives. Presently, peptides have been applied in a various manner to replace conventional antibody alternative therapeutics due to merits such as: (a) suitable pharmacokinetics; (b) massive production; (c) low cytotoxicity; (d) inhibition of antigenicity; and (e) low production cost. As a therapeutic drug, the advantage of peptide includes: (a) low production cost; (b) high safety and responsiveness; (c) relatively low patent royalty; (d) inhibition of antibody production against peptide in itself according to rare exposure on undesirable immune system; and (e) feasible modification and outstanding accuracy via synthesis. However, since most of peptides exhibits low affinity and specificity to a particular protein target compared with antibody, there is a drawback that they may be not utilized in several application fields. Therefore, it has been urgently demanded in the art to develop a novel peptide-based antibody alternative to overcome demerits of peptides. In this connection, the present inventors have made intensive studies to develop a peptide molecule capable of specifically binding a biological target molecule with high affinity. It should be expected as a technique capable of identifying a new drug with high affinity and specificity in a high-throughput manner using a peptide with low affinity reported about very numerous targets.
Throughout this application, various publications and patents are referred and citations are provided in parentheses. The disclosures of these publications and patents in their entities are hereby incorporated by references into this application in order to fully describe this invention and the state of the art to which this invention pertains.